1. Field of the Invention
The present invention relates to a driving support device for a vehicle including a function of supporting driving of a driver so that a vehicle avoids a collision with an obstacle existing ahead of the vehicle and a function of supporting the driving of the driver so that the vehicle travels along a lane.
2. Description of the Related Art
Hitherto, there has been known a driving support device for a vehicle for carrying out collision avoidance support control. The collision avoidance support control is control to decelerate an own vehicle through automatic braking when an obstacle with which the own vehicle is likely to collide is detected by a sensor, e.g., a camera sensor or a radar sensor. Moreover, for example, as proposed in Japanese Patent Application Laid-open No. 2012-116403, there is known a driving support device for a vehicle for carrying out, in addition to the automatic braking, collision avoidance support control of a type of operating an electric power steering device, thereby automatically steering an own vehicle toward a direction away from an obstacle.
On the other hand, as proposed in Japanese Patent Application Laid-open No. 2014-142965, there is known a driving support device for a vehicle for carrying out lane travel support control. The lane travel support control is, for example, control to detect left and right white lines on a road through a camera sensor, set a target travel line (e.g., a centerline at the center position of the left and right white lines) within a travel lane based on those left and right white lines, and applying a steering torque to a steering mechanism so that a travel position of an own vehicle is maintained in a vicinity of the target travel line, thereby supporting a steering operation of a driver. Moreover, there is also known lane travel support control of a type of sounding a buzzer when the own vehicle is likely to deviate to the outside of the travel lane (left and right white lines), and applying a steering torque to the steering mechanism so that the own vehicle returns to within the travel lane. The former lane travel support control is generally referred to as lane keep assist control. The latter lane travel support control is generally referred to as lane departure prevention control.
Incidentally, there is conceived a driving support device for a vehicle incorporating both the collision avoidance support system for carrying out the collision avoidance support control through the automatic steering and the lane travel support system for carrying out the lane travel support control. Both of the support systems support the driving of the driver by carrying out the steering control for the steered wheels, but have different purposes of control from each other. Thus, a steering control amount when the steering control is carried out in the driving support device including both of the systems needs to be set while maintaining an appropriate relationship between both of the systems.